1. Field of the Invention
This invention relates to a multiflow gas-dynamic pressure-wave machine.
2. Discussion of the Related Art
Single-flow pressure-wave machines cause noise annoyance, which should be reduced in view of the constantly increasing demands of environmentalists and in the justified interest of the public.
For this purpose, various solutions have already been proposed. One of these proposals (CH-PS No. 398 184) provides for subdividing the height of the cells of the rotor, in which the pressure exchange between the gaseous working substance takes place, to produce several circular flows which are divided in the radial direction by circular cylindrical intermediate pipes in order to place the fundamental frequency of the sound vibrations above the upper audibility threshold of the human ear. In a first embodiment of such a rotor the divisions of the adjacent cells are randomly different, but equal in all flows, so that all cell walls of the cells adjacent to one another in the radial direction are in common radial planes, while in a second embodiment the cell walls of flows radially adjacent to one another are randomly mutually offset in the circumferential direction. In another embodiment, only one flow is provided, and the cell walls consist of curved pieces of sheet metal with ends bent in the shape of hooks, the latter can be cast integral in the hub pipe or in the outside jacket of the rotor. However, the intended effect is not achieved in all these embodiments since only several vibrations of the same frequency are superposed and the fundamental frequency is kept.
The described design further exhibits disadvantages relating to stability. As a result of the circular cross section of the intermediate pipes, of the cell walls which are uniformly thick and offset relative to one another, and of the different size cell divisions, thermal and centrifugal force stresses occur which cause deformations and overstresses of the rotor structure. In the last-named variant, because of the great elasticity of the cell walls, especially during speed variations, torsion vibrations of the walls also occur, which can disturb the pressure wave process.